1. Field of the Invention
The present invention relates to a liquid crystal display (hereinafter “LCD”) panel, and more particularly, to an apparatus and a method for testing a size of a unit LCD panel and status of cut surface after cutting LCD panels fabricated on a large mother substrate into individual unit LCD panels.
2. Discussion of the Related Art
In general, an LCD device displays a desired picture by individually supplying a data signal according to picture information to the liquid crystal cell arranged in a matrix form and controlling light transmittance through liquid crystal molecules of the liquid crystal cells.
In the LCD device, TFT (hereinafter “TFT”) array substrates are formed on a large mother substrate and color filter substrates are formed on an additional mother substrate. Then, by attaching the two mother substrates, a plurality of LCD panels are simultaneously formed. Because yield can be increased by simultaneously forming a plurality of LCD panels on a glass substrate of a large area, a process of cutting the attached two mother substrates into unit LCD panels is required.
Conventionally, the cutting processing includes forming a predetermined cutting line on the surface of the substrate with a pen having a higher hardness than the glass substrate and propagating a crack along the predetermined cutting line. The cutting process of the unit LCD panel will be described in detail with reference to the accompanied drawings.
FIG. 1 is a schematic plan view showing a unit LCD panel formed with a TFT array substrate and color filter substrate attached to face into each other.
In FIG. 1, the LCD panel 10 includes a picture display unit 13 having a plurality of liquid crystal cells arranged in a matrix form, a gate pad unit 14 connected to a plurality of gate lines of the picture display unit 13, and a data pad unit 15 connected to a plurality of data lines of the picture display unit 13.
The gate pad unit 14 and the data pad unit 15 are formed at the marginal portion of the TFT array substrate 1. The marginal portion does not overlap the color filter substrate 2.
The gate pad unit 14 supplies a scan signal supplied from the gate driver integrated circuit to the gate lines of the picture display unit 13. The data pad unit 15 supplies picture information supplied from the data driver integrated circuit to the data lines of the picture display unit 13.
The data lines receive picture information and the gate lines receive the scan signal. The data lines and gate lines cross orthogonally on the TFT array substrate 1 of the picture display unit 13. At each of the crossed portion, a thin film transistor (TFT) is formed for switching the liquid crystal cells that are defined by the crossing of the data and gate lines. A pixel electrode is formed in each liquid crystal cell to be connected to the TFT for driving the liquid crystal cell. Furthers a protective film is formed over the entire surface to protect the pixel electrode and the TFT.
A plurality of color filters are formed on the color filter substrate 2. The color filters for a cell region are separated from adjacent cell regions by a black matrix. Common transparent electrodes corresponding to the pixel electrodes are formed on the color filter substrate 2.
A cell gap is formed between the TFT array substrate 1 and the color filter substrate 2 so that the two substrates are spaced apart and face each other. The TFT array substrate 1 and the color filter substrate 2 are attached by a sealant (not shown) formed at the exterior of the picture display unit 13. A liquid crystal layer (not shown) is formed in the space between the TFT array substrate 1 and the color filter substrate 2.
FIG. 2 illustrates a cross-sectional view showing a plurality of unit LCD panels formed in the first mother substrate having the TFT array substrates and the second mother substrate having the color filter substrates.
As shown in FIG. 2, a plurality of unit LCD panels are formed in such a manner that one side of the unit LCD panel TFT array substrates 1 protrudes by as much as a dummy region 31 of the unit LCD panel color filter substrates.
The protrusion of the unit LCD panel is provided because the gate pad unit 14 and the data pad unit 15 are formed at the marginal portion provided by the protrusion where the TFT array substrates 1 and the color filter substrates 2 do not overlap.
Thus, the color filter substrates 2 formed on the second mother substrate 30 are formed to be isolated by as much as dummy regions 31 which correspond to the protrusions of the TFT array substrates 1.
Each unit LCD panel is disposed at the first and second mother substrates 20 and 30 so that the area of the first and the second mother substrates 20 and 30 are used at the maximum. Depending on a model of unit LCD panel being fabricated, the unit LCD panels are generally formed to be isolated by as much as the second dummy regions 32.
After the first mother substrate 20 where the TFT array substrates 1 are formed and the second mother substrate 30 where the color filter substrates 2 are formed are attached each other, the LCD panels are individually cut. The dummy regions 31 formed at the region where the color filter substrates 2 of the second mother substrate 30 are isolated and the second dummy regions 32 isolating the unit LCD panels, are simultaneously removed.
FIG. 3 is an exemplary view showing a testing apparatus for LCD panel according to related art.
As shown in FIG. 3, the testing apparatus comprises a first and a second testing bars 101 and 102 for testing the cutting status of longer sides of the unit LCD panel 100 (that is, a side where the data pad unit is formed and the opposite side of the unit LCD panel). A third and a fourth testing bars 103 and 104 for testing the cutting status of shorter sides of the unit LCD panel 100 (that is, a side where the gate pad unit is formed and the opposite of the unit LCD panel.
The first and second testing bars 101 and 102 test whether or not a burr remains on the longer sides of the unit LCD panel 100 in a touch method. The third and fourth testing bars 103 and 104 test whether or not a burr is remains on the shorter sides of the unit LCD panel 100 by the same method as the first and second testing bars 101 and 102.
On the other hand, the size of the unit LCD panel 100 can be varied according to the models of unit LCD panel being fabricated. Therefore, the first and second testing bars 101 and 102 and the third and fourth testing bars 103 and 104 are formed to have same lengths as the longer sides and the shorter sides, respectively of the largest unit LCD panel 100 that may be fabricated, and thereby, the test can be performed for all models of unit LCD panel 100.
Also, in the unit LCD panel 100, a color filter substrate 120 is stacked on a TFT array substrate 110, and two sides of the TFT array substrate 110 are formed to protrude beyond the color filter substrate 120. This is because that the gate pad unit and data pad unit are formed on the TFT array substrate 110 in a marginal portion that does not overlap the color filter substrate 120, as described with reference to FIG. 1.
Therefore, one of the longer sides and one of the shorter sides of the unit LCD panel 100 have a step shape. The first testing bar 101 corresponds to the one of the longer sides of the unit LCD panel 100 on which the data pad unit is formed. The third testing bar 103 corresponds to the one of the shorter sides of the unit LCD panel 100 on which the gate pad unit is formed. Thus, to test the longer sides of the unit LCD panel 100, the first testing bar 101 is formed to be engaged with the one of longer sides of the unit LCD panel 100 having the step shape. In addition, to test the shorter sides of the unit LCD panel 100, the third testing bar 103 is formed to be engaged with the one of shorter sides of the unit LCD panel 100 having the step shape.
Hereinafter, a testing method of unit LCD panel using the above apparatus will now be described with reference to the accompanying sequential exemplary views, FIGS. 4A to 4C.
As shown in FIG. 4A, the unit LCD panel 100 is loaded on a first table (not shown) including the first to fourth testing bars 101 to 104. At that time, the color filter substrate 120 is stacked on the TFT array substrate 110, and two sides of the TFT array substrate 110 are formed to protruded beyond the color filter substrate 120 by the gate pad unit and the data pad unit as described above. The first testing bar 101 is formed to be engaged with the one of the longer sides of the unit LCD panel 100 having the step shape caused by the data pad unit. The third testing bar 103 is formed to be engaged with the one of the shorter sides of the unit LCD panel 100 having the step shape caused by the gate pad unit.
Next, as shown in FIG. 4B, the first and second testing bars 101 and 102 test whether or not the burr remains on the longer sides of the unit LCD panel 100 in the touch method.
As shown in FIG. 4C, the third and fourth testing bars 103 and 104 test whether or not the burr remains on the shorter sides of the unit LCD panel 100 in the touch method.
As described above, the unit LCD panel 100 is determined whether it is fine or inferior by testing the longer and shorter sides of the unit LCD panel 100 using the first to fourth testing bars 101 to 104 in the touch method. After that, the unit LCD panels 100 that are fine are selected at a predetermined interval and are removed from the production line to test whether or not the cut size of the unit LCD panel 100 is appropriate using an extra measuring device.
According to the apparatus and the method for testing LCD panel of the related art, the burr remaining on the unit LCD panel is tested, and the unit LCD panel of good quality is extracted from the production line with a predetermined period to test whether or not the size of the cut unit LCD panel is appropriate using an extra measuring device. Therefore, an operator should move the unit LCD panel from the production line to the measuring device for testing the size of cut LCD panel and perform the size test on the measuring device.
The above processes are inconvenient, and the productivity is lowered since the time spent on testing the size of the cut unit LCD panel is increased.
In addition, an additional measuring device of high price is needed, and accordingly, costs for equipment and maintenance of the production line are increased, and thereby, the cost price of the product is also increased.
Also, the size test is performed by sampling the unit LCD panels a predetermined interval, and therefore, reliability of the test is lowered. In addition, if the unit LCD panel is determined to be inferior, the operation is stopped, and all unit LCD panels from the panel previously sampled to the panel which will be sampled next should be tested and determined whether they are inferior or fine. Therefore, the unit LCD panels which have undergone post-processes may be discarded, and accordingly, material and time can be wasted.